This invention relates to a seat belt retractor for motor vehicle applications and particularly to one having a switch assembly for providing an output when a predetermined amount of seat belt webbing is withdrawn from the retractor.
Modern motor vehicles are required to have an occupant collision protection system. The most popular of such systems are seat belts which physically restrain the occupants during vehicle impacts and maneuvers. As a means of reminding the occupant of the necessity of deploying the restraint system, a warning light or other indicator is often provided. One approach for controlling such a warning indicator is to detect extension of the seat belt webbing which occurs when the belt is deployed.
In accordance with the present invention, a seat belt retractor is provided having a switch assembly incorporating a grooved cam plate which rotates with the retractor spool and has a spiral cam groove formed on one radial surface thereof. A follower which is confined to move in a radial direction engages the cam grooves. Rotation of the spool and cam causes the follower to move in a radial direction. Electrical contacts are actuated in response to the position of the follower to control auxiliary systems such as warning indicators.
The switch assembly in accordance with this invention is extremely simple in construction and has a minimum of moving parts. In addition, the mechanism can be compactly packaged into a retractor which is a considerable advantage in view of the stringent packaging constraints imposed on present motor vehicle designs.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.